shorter exposure, less noise. You can see that most easily with very long exposures, where dark frame subtraction is used to cancel out some of the noise.

From what I understand, back with the early digitals, yes, long exposures could lead to noise, as well as film... Long exposure noise is pretty much a moot point anymore...

With the C.Fn for long exposure NR set to Auto, dark frame subtraction is applied automatically to exposures of 1 second or longer, "...if noise typical of a long exposure is detected," (quote from the 7D manual, p. 208). So I guess Canon doesn't think long exposure noise is a moot point...

shorter exposure, less noise. You can see that most easily with very long exposures, where dark frame subtraction is used to cancel out some of the noise.

From what I understand, back with the early digitals, yes, long exposures could lead to noise, as well as film... Long exposure noise is pretty much a moot point anymore...

With the C.Fn for long exposure NR set to Auto, dark frame subtraction is applied automatically to exposures of 1 second or longer, "...if noise typical of a long exposure is detected," (quote from the 7D manual, p. 208). So I guess Canon doesn't think long exposure noise is a moot point...

I just checked my 7D... long exposure NR is set to OFF.... still no noise

shorter exposure, less noise. You can see that most easily with very long exposures, where dark frame subtraction is used to cancel out some of the noise.

From what I understand, back with the early digitals, yes, long exposures could lead to noise, as well as film... Long exposure noise is pretty much a moot point anymore...

With the C.Fn for long exposure NR set to Auto, dark frame subtraction is applied automatically to exposures of 1 second or longer, "...if noise typical of a long exposure is detected," (quote from the 7D manual, p. 208). So I guess Canon doesn't think long exposure noise is a moot point...

Just to be clear, it's CF 2, setting 1, it is set to off. This is just not that big of a deal. Personally I dont really trust in camera NR due to smearing that was famous with the 5d II so I usually turn NR to off or low if i have the option to do NR in post if needed.

I just checked my 7D... long exposure NR is set to OFF.... still no noise

I'm glad you don't see noise in your shots in your applications, but it doesn't mean it's not there. Noise is present in every image, but the amount obviously varies, as does the impact, and the latter is certainly dependent on the application (cropping, on-screen viewing, small prints, large prints, pixel peeping, etc.).

Long exposure noise is different than high ISO noise, in that the former is reproducible for a given exposure time and sensor temperature, whereas the latter is random. Thus, long exposures can have NR applied quite effectively in-camera (the computation is very simple, literally just subtracting the e- recorded at each photosite in the dark frame from the same photosite in the image). NR for high ISO is much more computationally intensive, and a computer will do that better than the on-board chipset. Also, post-processing NR for long exposures is not the same as NR for ISO noise. Unless you plan ahead and shoot a dark frame, you can't do long exposure NR in post. Many astrophotographers keep libraries of dark frames at various exposure times and temperature conditions and apply those in post, because it speeds up the image capture (i.e. you can just take a set of 30 s exposures abck to back, instead of the in-camera process of 30 s exposure followed by a 30 s dark frame).

I just checked my 7D... long exposure NR is set to OFF.... still no noise

I'm glad you don't see noise in your shots in your applications, but it doesn't mean it's not there. Noise is present in every image, but the amount obviously varies, as does the impact, and the latter is certainly dependent on the application (cropping, on-screen viewing, small prints, large prints, pixel peeping, etc.).

Long exposure noise is different than high ISO noise, in that the former is reproducible for a given exposure time and sensor temperature, whereas the latter is random. Thus, long exposures can have NR applied quite effectively in-camera (the computation is very simple, literally just subtracting the e- recorded at each photosite in the dark frame from the same photosite in the image). NR for high ISO is much more computationally intensive, and a computer will do that better than the on-board chipset. Also, post-processing NR for long exposures is not the same as NR for ISO noise. Unless you plan ahead and shoot a dark frame, you can't do long exposure NR in post. Many astrophotographers keep libraries of dark frames at various exposure times and temperature conditions and apply those in post, because it speeds up the image capture (i.e. you can just take a set of 30 s exposures abck to back, instead of the in-camera process of 30 s exposure followed by a 30 s dark frame).

I will say I haven't attempted astrophotography in almost 6-7 years (and even with that I shot with my medium format camera)... I guess I suppose having the the camera on bulb for a few minutes at a time if not longer with humidity and cold temperatures (situations which digital cameras struggle and have to work harder) then noise would be visible... I'm lucky enough to be in a dry climate with warm summer nights so I wouldn't have the same situation humidity wise as if I was sea level at lets say san fran or the midwest... (I had to do a shoot in chicago in which the humidity was so high (99%) my 30D at the time quit working until i got it in an air conditioned room to cool down and dry out.

Most of my long exposure stuff is for things like fireworks/lightning and high end architecture at twinight and usually (with digital) I dont get exposures longer than 30 seconds and typically noise at low iso is no problem for what I use it for. (film with reciprocity my long exposures get a heck of a lot longer to make up for it)

...I guess I suppose having the the camera on bulb for a few minutes at a time if not longer with humidity and cold temperatures (situations which digital cameras struggle and have to work harder) then noise would be visible... I'm lucky enough to be in a dry climate with warm summer nights...

Actually, cold is better. A major component of dark noise is thermal, and noise goes up with temperature. The image sensors on the cameras I use for microscopic imaging (where exposures in the 2-4 s range are needed to capture fluorescence) are Peltier-cooled to sub-zero temperatures to reduce dark noise.

I wasn't intending on being condescending and or rude, I was just seeking clarification about how you said you had it, tested it, and loved it and then "just got it" the other and are having buyers remorse. Do keep in mind regarding distortion... this lens is designed as a 17-40 on a full frame camera... 17mm on any camera will have some level of distortion... Same as the 17-55 in some regards on the 17 end, as well as lets say the tokina lens and the 16-35 I or II... The full frame will show the distortion more than crops, but it's still there.

Ah okay! It was just a misunderstanding then. My apologies. I agree that that there will always be some sort of distortion. However I have learned that photoshop has a feature built into CameraRAW that can fix most distortion problems. This will come in handy, though I do need to get a legitimate copy of photoshop since I cannot borrow my friend's forever. That's gonna be a little pricy.

Quote

Some lenses to keep in consideration that will have fast(er) speeds and keep distortion in check (20mm 2.8, 24mm 1.4, 24mm 2.8, 35mm 1.4, they are all within the range of the 17-40, should keep distortion better in check, and 2.8 or faster) It's a great outdoors/travel/walk-around lens, but indoors, you will need to have a fast prime if you really want to shoot handhold. I do architecture (one of my specialties) and real estate photos... I shoot with the 10-20 and 17-40... But then again I shoot low apertures, tripod always, and they are static. Sometimes if I cant shoot tripod I still use low ISO but throw in off camera flash or strobe. Light will always be an issue indoors so either use a faster lens or use a flash (ideally either strobe or off camera flash). The 7D has a great commander feature if you can pick up some 580's or 430's... scatter them around the scene out of view from the camera and you never have to worry about lack of light.

I am in need of a good tripod. Somebody recommended manfrotto and I'm currently weighing my options.

Lighting is something I'll definitely need to invest in. Before getting external flash, though, I want to try to make the pictures as good as possible without flash. Force myself to practice, so to speak. You have some good suggestions here.

Quote

I never said it was foolish not getting the 17-55... I said I liked the 17-40 personally, however you need to really and fully know it's capabilities and limitations to get the most out of it.

I mixed you up with somebody else who said that to me, oops.

Quote

By going in a shoot fully educated on your gears limits will allow you to forward think so you know how to counter the limitations and push the limits to get awesome shots. Also remember the 17-40 can be used by the 7d and 5d whereas the 17-55 can only be used on crop cameras. Regarding your expectations of high ISO, check out the link i posted earlier... it'll give you a good idea of what this camera can do not only against itself but competitors.

...I guess I suppose having the the camera on bulb for a few minutes at a time if not longer with humidity and cold temperatures (situations which digital cameras struggle and have to work harder) then noise would be visible... I'm lucky enough to be in a dry climate with warm summer nights...

Actually, cold is better. A major component of dark noise is thermal, and noise goes up with temperature. The image sensors on the cameras I use for microscopic imaging (where exposures in the 2-4 s range are needed to capture fluorescence) are Peltier-cooled to sub-zero temperatures to reduce dark noise.

I thought cold would be worse (batteries lose power, computers get sluggish, etc..) but i'll take your word for it because I have no reason why not to in this situation.

I wasn't intending on being condescending and or rude, I was just seeking clarification about how you said you had it, tested it, and loved it and then "just got it" the other and are having buyers remorse. Do keep in mind regarding distortion... this lens is designed as a 17-40 on a full frame camera... 17mm on any camera will have some level of distortion... Same as the 17-55 in some regards on the 17 end, as well as lets say the tokina lens and the 16-35 I or II... The full frame will show the distortion more than crops, but it's still there.

Ah okay! It was just a misunderstanding then. My apologies. I agree that that there will always be some sort of distortion. However I have learned that photoshop has a feature built into CameraRAW that can fix most distortion problems. This will come in handy, though I do need to get a legitimate copy of photoshop since I cannot borrow my friend's forever. That's gonna be a little pricy.

Quote

Some lenses to keep in consideration that will have fast(er) speeds and keep distortion in check (20mm 2.8, 24mm 1.4, 24mm 2.8, 35mm 1.4, they are all within the range of the 17-40, should keep distortion better in check, and 2.8 or faster) It's a great outdoors/travel/walk-around lens, but indoors, you will need to have a fast prime if you really want to shoot handhold. I do architecture (one of my specialties) and real estate photos... I shoot with the 10-20 and 17-40... But then again I shoot low apertures, tripod always, and they are static. Sometimes if I cant shoot tripod I still use low ISO but throw in off camera flash or strobe. Light will always be an issue indoors so either use a faster lens or use a flash (ideally either strobe or off camera flash). The 7D has a great commander feature if you can pick up some 580's or 430's... scatter them around the scene out of view from the camera and you never have to worry about lack of light.

I am in need of a good tripod. Somebody recommended manfrotto and I'm currently weighing my options.

Lighting is something I'll definitely need to invest in. Before getting external flash, though, I want to try to make the pictures as good as possible without flash. Force myself to practice, so to speak. You have some good suggestions here.

Quote

I never said it was foolish not getting the 17-55... I said I liked the 17-40 personally, however you need to really and fully know it's capabilities and limitations to get the most out of it.

I mixed you up with somebody else who said that to me, oops.

Quote

By going in a shoot fully educated on your gears limits will allow you to forward think so you know how to counter the limitations and push the limits to get awesome shots. Also remember the 17-40 can be used by the 7d and 5d whereas the 17-55 can only be used on crop cameras. Regarding your expectations of high ISO, check out the link i posted earlier... it'll give you a good idea of what this camera can do not only against itself but competitors.

Thanks

While at school, I used manfrottos tripods almost exclusively... We shot with 4x5's and medium formats so i needed heavy duty gear to handle the weight and strain of the cameras... I dont shoot much 4x5's any more but now my gear includes a Slik Pro 700 legs (i think thats the number) and manfrotto heads... The legs are aluminum and light weight compared to my old heavy duty manfrottos... I would love a carbon fiber manfrotto or better, but the slik is light weight yet extremely sturdy for me. Keep weight and load in mind... Weight because you have to haul this puppy with you on shoots and load because if the head AND legs aren't strong enough to hold secure your gear, you can not only lose shots but damage your gear. I had an old tripod fail on me wading in a river waiting for the lighting to be right before I shot the image... I barely caught the camera in time before it fell in the river.

Go to your local store and they should have a nice selection of tripods... feel them, hold them, and do your research. Regarding the photoshop... look on craigslist and look at your local colleges... A lot of them sell photoshop and or creative suite at student prices... At my local university in nevada, they have the entire creative suite for $299 student price. Fully legit copy. I knew a few college students there but see if your local college has software discounts at the student store. Also keep in mind adobe typically has a product cycle on a strong 18 month cycle... CS6 should be out sometime in the second/third quarter of 2012 so perhaps you will see CS5 at a discounted price. Lastly, i heard adobe now has a subscription option? You pay a monthly fee and you get to use their software... Doing that for i think for a few months pays for the entire purchase price but if you need to have it now and cant pony up $699, then that's a good option.

One last thing to consider with tripods is leg flexibility... Manfrotto on a lot of legs have a sliding locking horizontal support bar that connects to the legs to the center column. You will want to be able to control each leg individually.. Sometimes you may be on unstable grounds in which one leg is shooting out at the standard 30 degrees angle and another leg, given your location, maybe 50-60 degrees, etc.... If you dont have that control on your legs, it can hinder your photo shoot. You will know what i'm talking about as you play with the tripods... lastly on heads, see if you can get a nice sturdy ball head. Ball heads carry the weight better over the tripod where as standard pan/tilt heads are cheaper but instead of holding the weight directly on the body, you are carrying the weight on a few screws and metal/plastic as it hovers above the center column. It's just not as secure. Manfrotto has high quality heavy duty pan/tilts but you still can beat a nice ballhead.

lady

One last thing to consider with tripods is leg flexibility... Manfrotto on a lot of legs have a sliding locking horizontal support bar that connects to the legs to the center column. You will want to be able to control each leg individually.. Sometimes you may be on unstable grounds in which one leg is shooting out at the standard 30 degrees angle and another leg, given your location, maybe 50-60 degrees, etc.... If you dont have that control on your legs, it can hinder your photo shoot. You will know what i'm talking about as you play with the tripods... lastly on heads, see if you can get a nice sturdy ball head. Ball heads carry the weight better over the tripod where as standard pan/tilt heads are cheaper but instead of holding the weight directly on the body, you are carrying the weight on a few screws and metal/plastic as it hovers above the center column. It's just not as secure. Manfrotto has high quality heavy duty pan/tilts but you still can beat a nice ballhead.

I wasn't intending on being condescending and or rude, I was just seeking clarification about how you said you had it, tested it, and loved it and then "just got it" the other and are having buyers remorse. Do keep in mind regarding distortion... this lens is designed as a 17-40 on a full frame camera... 17mm on any camera will have some level of distortion... Same as the 17-55 in some regards on the 17 end, as well as lets say the tokina lens and the 16-35 I or II... The full frame will show the distortion more than crops, but it's still there.

Ah okay! It was just a misunderstanding then. My apologies. I agree that that there will always be some sort of distortion. However I have learned that photoshop has a feature built into CameraRAW that can fix most distortion problems. This will come in handy, though I do need to get a legitimate copy of photoshop since I cannot borrow my friend's forever. That's gonna be a little pricy.

Quote

Some lenses to keep in consideration that will have fast(er) speeds and keep distortion in check (20mm 2.8, 24mm 1.4, 24mm 2.8, 35mm 1.4, they are all within the range of the 17-40, should keep distortion better in check, and 2.8 or faster) It's a great outdoors/travel/walk-around lens, but indoors, you will need to have a fast prime if you really want to shoot handhold. I do architecture (one of my specialties) and real estate photos... I shoot with the 10-20 and 17-40... But then again I shoot low apertures, tripod always, and they are static. Sometimes if I cant shoot tripod I still use low ISO but throw in off camera flash or strobe. Light will always be an issue indoors so either use a faster lens or use a flash (ideally either strobe or off camera flash). The 7D has a great commander feature if you can pick up some 580's or 430's... scatter them around the scene out of view from the camera and you never have to worry about lack of light.

I am in need of a good tripod. Somebody recommended manfrotto and I'm currently weighing my options.

Lighting is something I'll definitely need to invest in. Before getting external flash, though, I want to try to make the pictures as good as possible without flash. Force myself to practice, so to speak. You have some good suggestions here.

Quote

I never said it was foolish not getting the 17-55... I said I liked the 17-40 personally, however you need to really and fully know it's capabilities and limitations to get the most out of it.

I mixed you up with somebody else who said that to me, oops.

Quote

By going in a shoot fully educated on your gears limits will allow you to forward think so you know how to counter the limitations and push the limits to get awesome shots. Also remember the 17-40 can be used by the 7d and 5d whereas the 17-55 can only be used on crop cameras. Regarding your expectations of high ISO, check out the link i posted earlier... it'll give you a good idea of what this camera can do not only against itself but competitors.

Thanks

While at school, I used manfrottos tripods almost exclusively... We shot with 4x5's and medium formats so i needed heavy duty gear to handle the weight and strain of the cameras... I dont shoot much 4x5's any more but now my gear includes a Slik Pro 700 legs (i think thats the number) and manfrotto heads... The legs are aluminum and light weight compared to my old heavy duty manfrottos... I would love a carbon fiber manfrotto or better, but the slik is light weight yet extremely sturdy for me. Keep weight and load in mind... Weight because you have to haul this puppy with you on shoots and load because if the head AND legs aren't strong enough to hold secure your gear, you can not only lose shots but damage your gear. I had an old tripod fail on me wading in a river waiting for the lighting to be right before I shot the image... I barely caught the camera in time before it fell in the river.

Go to your local store and they should have a nice selection of tripods... feel them, hold them, and do your research. Regarding the photoshop... look on craigslist and look at your local colleges... A lot of them sell photoshop and or creative suite at student prices... At my local university in nevada, they have the entire creative suite for $299 student price. Fully legit copy. I knew a few college students there but see if your local college has software discounts at the student store. Also keep in mind adobe typically has a product cycle on a strong 18 month cycle... CS6 should be out sometime in the second/third quarter of 2012 so perhaps you will see CS5 at a discounted price. Lastly, i heard adobe now has a subscription option? You pay a monthly fee and you get to use their software... Doing that for i think for a few months pays for the entire purchase price but if you need to have it now and cant pony up $699, then that's a good option.

One last thing to consider with tripods is leg flexibility... Manfrotto on a lot of legs have a sliding locking horizontal support bar that connects to the legs to the center column. You will want to be able to control each leg individually.. Sometimes you may be on unstable grounds in which one leg is shooting out at the standard 30 degrees angle and another leg, given your location, maybe 50-60 degrees, etc.... If you dont have that control on your legs, it can hinder your photo shoot. You will know what i'm talking about as you play with the tripods... lastly on heads, see if you can get a nice sturdy ball head. Ball heads carry the weight better over the tripod where as standard pan/tilt heads are cheaper but instead of holding the weight directly on the body, you are carrying the weight on a few screws and metal/plastic as it hovers above the center column. It's just not as secure. Manfrotto has high quality heavy duty pan/tilts but you still can beat a nice ballhead.

I wasn't intending on being condescending and or rude, I was just seeking clarification about how you said you had it, tested it, and loved it and then "just got it" the other and are having buyers remorse. Do keep in mind regarding distortion... this lens is designed as a 17-40 on a full frame camera... 17mm on any camera will have some level of distortion... Same as the 17-55 in some regards on the 17 end, as well as lets say the tokina lens and the 16-35 I or II... The full frame will show the distortion more than crops, but it's still there.

Ah okay! It was just a misunderstanding then. My apologies. I agree that that there will always be some sort of distortion. However I have learned that photoshop has a feature built into CameraRAW that can fix most distortion problems. This will come in handy, though I do need to get a legitimate copy of photoshop since I cannot borrow my friend's forever. That's gonna be a little pricy.

Quote

Some lenses to keep in consideration that will have fast(er) speeds and keep distortion in check (20mm 2.8, 24mm 1.4, 24mm 2.8, 35mm 1.4, they are all within the range of the 17-40, should keep distortion better in check, and 2.8 or faster) It's a great outdoors/travel/walk-around lens, but indoors, you will need to have a fast prime if you really want to shoot handhold. I do architecture (one of my specialties) and real estate photos... I shoot with the 10-20 and 17-40... But then again I shoot low apertures, tripod always, and they are static. Sometimes if I cant shoot tripod I still use low ISO but throw in off camera flash or strobe. Light will always be an issue indoors so either use a faster lens or use a flash (ideally either strobe or off camera flash). The 7D has a great commander feature if you can pick up some 580's or 430's... scatter them around the scene out of view from the camera and you never have to worry about lack of light.

I am in need of a good tripod. Somebody recommended manfrotto and I'm currently weighing my options.

Lighting is something I'll definitely need to invest in. Before getting external flash, though, I want to try to make the pictures as good as possible without flash. Force myself to practice, so to speak. You have some good suggestions here.

Quote

I never said it was foolish not getting the 17-55... I said I liked the 17-40 personally, however you need to really and fully know it's capabilities and limitations to get the most out of it.

I mixed you up with somebody else who said that to me, oops.

Quote

By going in a shoot fully educated on your gears limits will allow you to forward think so you know how to counter the limitations and push the limits to get awesome shots. Also remember the 17-40 can be used by the 7d and 5d whereas the 17-55 can only be used on crop cameras. Regarding your expectations of high ISO, check out the link i posted earlier... it'll give you a good idea of what this camera can do not only against itself but competitors.

Thanks

While at school, I used manfrottos tripods almost exclusively... We shot with 4x5's and medium formats so i needed heavy duty gear to handle the weight and strain of the cameras... I dont shoot much 4x5's any more but now my gear includes a Slik Pro 700 legs (i think thats the number) and manfrotto heads... The legs are aluminum and light weight compared to my old heavy duty manfrottos... I would love a carbon fiber manfrotto or better, but the slik is light weight yet extremely sturdy for me. Keep weight and load in mind... Weight because you have to haul this puppy with you on shoots and load because if the head AND legs aren't strong enough to hold secure your gear, you can not only lose shots but damage your gear. I had an old tripod fail on me wading in a river waiting for the lighting to be right before I shot the image... I barely caught the camera in time before it fell in the river.

Go to your local store and they should have a nice selection of tripods... feel them, hold them, and do your research. Regarding the photoshop... look on craigslist and look at your local colleges... A lot of them sell photoshop and or creative suite at student prices... At my local university in nevada, they have the entire creative suite for $299 student price. Fully legit copy. I knew a few college students there but see if your local college has software discounts at the student store. Also keep in mind adobe typically has a product cycle on a strong 18 month cycle... CS6 should be out sometime in the second/third quarter of 2012 so perhaps you will see CS5 at a discounted price. Lastly, i heard adobe now has a subscription option? You pay a monthly fee and you get to use their software... Doing that for i think for a few months pays for the entire purchase price but if you need to have it now and cant pony up $699, then that's a good option.

Good suggestions! Thanks!

If you tell me your budget you would be willing to spend (on the set) I can give you specific suggestions... There are SO MANY brands and quality types it really is very broad.

I use a Manfrotto 190CXPRO4 with a 488RC2 ballhead. It's a great tripod, and it easily supports a gripped body and big white zoom (100-400mm or 70-200mm f/2.8L IS II).

Manfrotto makes both aluminum and carbon fiber (CX in the name) legs. Carbon fiber is lighter, damps vibration better than aluminum, and is easier to handle in the cold (aluminum feels much colder to the touch), but it's more expensive. For both aluminum and carbon fiber, the 190 series has smaller diameter tubes, the 055 series has larger diameter tubes (bigger tubes support more weight). The number on the end of the CX series names is 3 or 4, and refers to the number of sections in the legs. Some will say fewer sections is more stable, but 3- and 4-section tripods have the same weight specification. More sections means a shorter folded length, but also an extra set of sections to extend so setup takes slightly longer.

I picked the 190CXPRO4 for it's light weight and the fact that when folded, it will fit in a carry-on rollerboard suitcase (the 3-section version is too long, although if you remove the ballhead it should fit - but that's a pain because it requires carrying tools).

I think the Manfrotto legs with the horizontal bars are the video supports, defnintely stay away from those.

They can do video but we needed them for our 4x5's and shoot, you could set them up near a tornado and they probably would stay still haha. Plus the quick release legs were wonderful but VERY heavy and overkill if you dont need it.

I use a Manfrotto 190CXPRO4 with a 488RC2 ballhead. It's a great tripod, and it easily supports a gripped body and big white zoom (100-400mm or 70-200mm f/2.8L IS II).

The number on the end of the CX series names is 3 or 4, and refers to the number of sections in the legs. Some will say fewer sections is more stable, but 3- and 4-section tripods have the same weight specification. More sections means a shorter folded length, but also an extra set of sections to extend so setup takes slightly longer.

I would be among the few who say the more sections it is the less stable it is on the heavier gear... Then again the same can be said by extending the center column. The more sections, the taller it potentially can get but only you can gauge how important that is for you. His tripod is a very nice tripod and a hair over $300 on adorama legs only. I would recommend an action grip ball head such as:

They are all excellent choices however they each have their own quirks...

http://www.adorama.com/BG190CX3.html... another nice choice with 3 sections... But dont take my word for it.. go to your local store/stores and look at them... hold them... operate them... see what feels best for you given your new knowledge about tripods.

http://www.adorama.com/BG190CX3.html... another nice choice with 3 sections... But dont take my word for it.. go to your local store/stores and look at them... hold them... operate them... see what feels best for you given your new knowledge about tripods.

Did a double-take there, 190CX3 vs. 190CXPRO3. The "pro" version has a CF center column (the CX3 has an aluminum center column). Probably more importantly, the CXPRO3 has the adjustable center column - it can be turned 90Â° or even 180Â° to hang upside down from the legs, which I've used for a close-to-the-ground perspective on macro and landscape shots.

The difference between 3- and 4-section legs is probably real, but minor (I've tried both, and while the 3-section version 'feels' more stable, test shots with the same camera/lens on both did not show a difference). Raising the center column definitely reduces stability - that effect is far greater than the difference in number of leg sections.